Use latest grpc version (v1.39.0) for cmake build of otlp exporter.

[lalitb]

Changes

• Use the latest grpc version ( v1.39.0) for cmake builds of otlp exporter when compiled with g++5.1 or greater
• Use the compatible grpc version (v1.33.2) for cmake builds of otlp exporter when compiled with g++4.8 or g++5.0 compiler.
• Add github workflow to build otlp exporter using g++4.8 compiler ( with grpc v1.33.2 )
• Install abseil C++ library - as grpc v1.39.0 service api has a dependency on this library ( and we use this for otlp mock)

we still need similar support for bazel. As of now, bazel builds uses grpc v1.33.2.

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[codecov]

Codecov Report

Merging #927 (90ecacf) into main (5067e49) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #927   +/-   ##
=======================================
  Coverage   95.36%   95.36%           
=======================================
  Files         160      160           
  Lines        6779     6779           
=======================================
  Hits         6464     6464           
  Misses        315      315           

[ThomsonTan]

What is this for?

[lalitb]

This is actually copied from here (existing otlp build action on ubuntu-latest):

opentelemetry-cpp/ci/do_ci.sh

Line 103 in ef16d00

sed -i "s~gRPC_CPP_PLUGIN_EXECUTABLE-NOTFOUND~$grpc_cpp_plugin~" ${proto_make_file} #fixme

Somehow, cmake is not able to find the grpc_cpp_plugin executable during configuration and so it has to be replaced manually in generated make file before doing the actual make.
I will debug this separately and fix in another PR.

[linux-foundation-easycla]

The committers are authorized under a signed CLA.

• ✅ Lalit Kumar Bhasin (b221f18, 48bef11, 72fa16d, 4d48715, 1ac7be7, 007af85, 5b87519, 5c1bda5, a14806f, 0d28b9c, 4744d5f, 7da8fcf, 90ecacf)